This invention relates to an air-laydown apparatus for assembling textile fibers into webs, and is more particularly concerned with improvements in dispersing and transporting textile fibers in an air stream for collection on a moving screen to form webs which are suitable for use in producing high quality nonwoven fabric.
Nonwoven fabrics are produced from fibrous webs by bonding or interlocking the fibers to provide durability and strength. The fibers of the web may be hydraulically entangled by treatment with high energy liquid streams as disclosed in Evans U.S. Pat. No. 3,485,706, issued Dec. 23, 1969. When producing relatively heavy weight textile fabric, Lauterbach U.S. Pat. No. 2,910,863, issued Nov. 3, 1959, discloses that fiber interlocking may be initiated by treatment with a needle loom and completed by crimping or shrinking the fibers. Production of bonded nonwoven fabrics may be accomplished as disclosed in Graham U.S. Pat. No. 2,765,247, issued Oct. 2, 1956. The quality of fabric produced by these methods depends upon the quality and uniformity of the web which is treated.
Webs suitable for producing high quality nonwoven fabrics, by treatments of the above type, can be prepared by air laydown of textile fibers. Prior art air-laydown processes and apparatus are illustrated by Miller U.S. Pat. No. 3,768,120 issued Oct. 30, 1973, Zafiroglu U.S. Pat. No. 3,906,588 issued Sept. 23, 1975 and Neuenschwander U.S. Pat. No. 4,176,427 issued Dec. 4, 1979. Staple fibers are shipped as a compacted mass. Conventional picking and carding operations are used to separate the fibers. The resulting loosely opened fiber lap is fed to a toothed disperser roll and a stream of air is sucked or blown over the roll. The roll is rotated at high speed to feed the fibers into the air stream, the objective being to feed individual fibers rather than clumps or groups of fibers. The fibers are carried by the air stream through a conduit to the screen surface of a condenser roll or conveyor, where the fibers are deposited over a relatively large surface area to form a layer on the moving screen. The Zafiroglu patent discusses the importance of air turbulence for providing a generally uniform distribution of fibers over relatively large areas throughout the conduit. The Miller patent discusses the importance of air-flow control means adjacent the opposite edges of the screen for shifting the fiber stream rapidly back and forth to even out fiber depositions so that streaks do not form.